Open hole carrier



Oct. 2, 195-6 Filed Sept. 17. 1949 R. T. HARCUS OPEN HOLE CARRIER 2Sheets-Sheet 1 208597 n HHEC'US,

INVENTOR.

RTTOIQ/JEVS' Oct. 2, 1956 R. T. HARCUS 2,764,938

OPEN HOLE CARRIER 2 Sheets-Sheet 2 Filed Sept. 17, 1949 205527 z M ecus,

IN V EN TOR.

United States Patent OPEN HOLE CARRIER Robert Trail] Harcus, Long Beach,Calif., assignor, by

mesne assignments, to Borg-Warner Corporation, Chicage, 11]., acorporation of Illinois This invention relates to the penetrating of oilstrata and particularly to a carrier and means for accomplishing thispurpose.

It is well known that considerable amounts of oil exist in reservoirsbelow the surface of the earth which may have been tapped by wells butfrom which oil is either locked out by natural or man-made barrierswhich prevent its recovery. Such natural barriers may consist of hard,tight formations in which the oil is stored, the permeability of whichis of such a low order that the oil cannot flow through the intersticesand drain into the well. Formations of this type may be either limestoneor dense sandstone.

Man-made barriers to the flow of oil from the reservoir into the wellmay exist as the result of the building up on the walls of the hole ofan impermeable sheath formed by the action of the drilling mud, or mayresult from water or other filtrate from the drilling fiuid permeatingand wetting the surrounding formation for a distance of from severalinches to a foot or more. Such mud sheath or water-wet zone surroundingthe well must somehow be perforated in order to obtain production.

. Prior practice with tight natural formations was to set off heavycharges of nitroglycerin in the well and, while this undoubtedly in manycases aids production in such tight formations, by reason of thedispersed effect of the explosion its effectiveness is limited and,further, the use of large amounts of nitroglycerin or similar explosivesis dangerous to Well equipment and must be followed b extensive cleaningout and bailing operations.

As regards man-made barriers, prior practice has been to attempt topenetrate the mud sheath'or water-wet zone by the use of bullets, but itis difficult to impart to the bullets the energy necessary to bringabout desired penetration.

Again, in many old wells wherein a good flow from reservoir to well hadonce existed, production becomes lower due to a clogged sand conditionin the vicinity of the well bore, or where parafiin or other substanceshave coated the producing zone causing a decrease in the rate of flow.Here, as above, bullets have been used in an attempt to perforate suchcongested zones but subject to the same limitations as to penetrabilityas set forth above.

And further, aside from primary oil flow, certain practices are in usein the oil industry today which require or are greatly enhanced by theopening up of the oilbearing formations. For example, with limestoneformations it is common practice to treat the formations with acid toenlarge the interstices of the formation and thus facilitate the flow ofoil into the well. If deep channels into the formation could be opened,the acidizing would be much more effective. Non-directional blasting hasnot been effective enough to do this because the energy is notconcentrated enough; similarly bullet perforating has also provenunsatisfactory because'of inadequate penetration and the bulletsremaining to block the channels they create. a

In addition to practices such as acidizing, certain secondary recoverymethods, as Water-flooding or gas injection, would be facilitated by thepenetration of any natural or man-made barrier which might impede theHow of the driving medium into the formation.

In an effort to provide means for accomplishing the penetration throughnatural or man-made barriers from Well into formation and to open up theformation to enhance the flow of oil therefrom, recourse has been had tothe use of lined shaped charges. Such charges are explosives but, ascontrasted with previous nitroglycerin practice, are explosives having ahighly effective directional effect. Indeed such explosives, in additionto pro- "idinga directional efliect achieve, by the provision of acavity in the surface of an explosive, a liner in said cavity, and aclosure for said lined cavity, an entirely new and different explosiveeffect, namely, the formation from the liner of a thin pencil-like jettraveling through the barrier and into the formation at speeds believedto exceed the rate of advance of the detonation wave of the explosiveitself. However, difficulty in the use of such lined shaped charges hasbeen occasioned by several factors. First, while a retrievable metal gunbody carrying the charges might be thought advisable for lowering thecharges into the well to the vicinity of the oil-bearing formation, theamount of explosive required for the charges, the general structure ofthe charges, the necessity of providing firing means for the charges andthe limited confines of the Well bore, have indicated that theretrievable gun is impractical, due to its space requirements.

Second, recourse to a dispensable carrier for the charges has presentedthe problem that the debris from the carrier, following its destructionby the explosive charges, is left in the well.

Third, assuming that a dispensable carrier may be built light enough andsufliciently frangible and drillable so that its remaining in the wellwill not make the whole operation infeasible, such carrier must not onlybe capable of carrying the charges in properly disposed positions, butit must be of a structure capable of securing the charges and capable ofprotecting the charges and associated firing means during the loweringof the carrier through the well bore to the oil-bearing formation.

It is therefore a general object of this invention to provide a meansfor achieving the opening up of tight formations by penetrationthereinto, whether directly or through barriers such as mud sheaths orwater-wet zones.

It is a further object of this invention to provide a novel andpracticable shaped charge assembly.

Again it is an object of this invention to provide a carrier adapted tosupport and position shaped charges and their firing means as they arelowered into the well.

Moreover, it is another object of the invention to provide a carrier forshaped charges of simple, frangible, drillable construction, so thatafter detonation of the shaped charges within a well the remnants of thecarrier will not interfere unduly with subsequent operations in thewell.

His a still further object of the invention to provide a shaped chargecarrier of light construction, but still capable of safely securing andprotecting shaped charges 1 and 2, the carrier comprises a plurality offace members forming a polygon adapted to be affixed to an adapter 12 bymeans of machine screws or bolts 14 passing through holes in the saidface members and in the adapter 12. The adapter 32 is provided with athreaded end 16 which may thread into a sub or other hole member whichis supported by a cable which may in turn be used for raising orlowering the unit in the well. The said adapter 12 is likewise providedwith a bore 18 and fitting 20, the purpose of which will be hereinafterdescribed.

The polygonal carrier frame 10 as shown herein may consist of fourfacemembers 22, 24, 26, 28, said face members being formed'of frangible,easily drillable material such as aluminum alloy and each terminating inflanges 30. The flanges 38 are utilized as a means for assembling thecarrier frame, said flanges being riveted together by the rivets 32 or,if it is desired,.being spotwelded. Such flanges, as will be seen,extend outwardly from the carrier itself and, as will be hereinafterexplained, form, a protective guard for the entire structure.

The carrier 10 is adapted to support a number of lined shaped chargeunits 34, each of said charge units consisting, in this embodiment ofthe invention, of a case 36 which may be of plastic or alloy material; aliner 38, which may be of metal but which is shown here as constructedof glass; a closure 40, the function of which is to exclude liquids fromthe cavity formed by the liner 38 and which is in this embodimentconstructed of glass and is integral with the liner 38; the explosive42', and booster 44. The liner-closure unit 3840 is cemented in placewithin the case 36, and the charge is fired by a detonating fuse 46passing through a groove 47 in the rear of the charge unit strunghelically through the holes 48 in the flanges 30 of the carrier, throughthe bore 18 of the adapter 12 to the fitting 20, where it is connectedto the conductor of the cable in common manner. Such detonating fuse mayconsist of the well known Primacord encased in a tube made of materialeasily disintegrated by the detonation of the fuse but strong enough totake the pressure of a high head of well liquid, in this embodimentaluminum alloy. It will be noted that the detonating fuse 46 terminatesin a fitting 50 affixed to a lower guide 52. Such lower guide mayconsist of vertical plates aflixed to the carrier structure by anycommon means.

As is apparent from the drawings, the face members 22, 24, 26 and 28 areprovided with a plurality of holes 54 cut to reduce weight in thecarrier and to provide less material which must remain at the bottom .ofthe hole. after operation of the unit. Each face member has interposedbetween the holes 54 the firing holes 56, alternating with charge ports58. The firing holes 56 permit the projection of the rearward end of thecharge unit therethrough to contact the detonating fuse 46, and thecharge ports 58 permit insertion of the charge unit into the carrier anda shooting of the jet through said ports.

Each charge unit. 34 is first inserted in a port 58 until its rearwardgroove 47 contacts the detonating fuse 46, whereupon a cap 60 consistingof a nose 62 and a fiat circular base 64. having projecting lugs 66 ispassed through the said port with said lugs 66 registering with cut-awayportions 68 in the face member until the base 64 contacts the closure 40of the charge unit. The cap 60 is then rotated until the lugs 66 engagein internal recesses in the face member formed by the raised portions 70of said face member. Since there is a certain resiliency in thedetonating fuse due to the encasing tube and the closure 40 of thecharge unit presses against the base 64 of the cap 62, the lugs 66 seatfirmlyin the recesses of the face member and secure the charge units.

As shown in Figure 1, proper aligning of the relative holes 54', 56 andports 58 of the various'face members permits the progressive positioningof the charge units -'at 90 transverse intervals or phasing. As shown inFigure 1, the rearward end of the uppermost charge unit is shown. Next,the second. charge unit is. pointed to. the. right. The third chargeunit is pointed at the observer, and the fourth charge unit is pointedto the left. This permits an effective pattern of penetration into theformation. Similarly, in an embodiment comprising an hexagonal carrier60 or even 120 phasing would be advantageous. It will be appreciatedthat the embodiment herein shown sets forth a four-charge-unit carrierand that many more charge units can be used in a, longer assembly.

Thus the invention comprises a frangible, drillablc, lightweightstructure, admirably suited for positioning the charge units in the mostadvantageous manner for efiicient penetration of the strata. It furtherprovides a handy means for locking the charge units into position.Again, due to the helical wrapping of the detonating fuse, such fusecontacts the booster end of the charge units without the necessity ofusing any excess of detonating fuse and in such manner that interferencebetween charges and premature explosions is eliminated. The pass ing ofsaid fuse through the flanges which extend beyond thesaid fuse not onlymeans that the charge units and the carrier itself are protected fromthe abrasive effect of the sides of the bore hole during lowering intothe well, but that the detonating fuse is likewise protected. Thecarrier containing the charge units may be lowered to a depth adjacentany formation desired to be opened up, the Primacord detonatedelectrically through the conductor of the cable in common manner, andthe lined shaped charges thus fired progressively, but due to the rapidrate of propagation of detonation along the fuse, almost simultaneously.The jets from the charges penetrate the mud sheath or water-wet zoneabout the. bore hole, or the tight formation, as the case may be, and

further. penetrate on into the formation. Cracks in the formationdevelop radially from the holes in the formation caused by the jets andthe formation is thus opened up either to increased production or to theforcing of secondary driving materials or acidizing materials into thesaid formation.

Figure 3 shows. a modification of the charge and chargesecuring means inthe carrier. The lined shaped charge unit here'shown comprises a case72; a liner, which in this instance may be. copper or other metal, 74; aclosure 76 not; integral with the liner but pressfitted into the case.and sealed by an O-ring 78; explosive 80; a booster 82; and a. metalseal 84 forming the groove through which the detonating fuse 86 passes.A hole 88 is provided, similar to the holes 54 but without the cut-awayportions 68, and through this hole is inserted the charge unit. In theface members 90 and 92 are provided angle members 94, punched from thesaid face members, and when the charge unit is passed into the carriersufliciently for its booster end to abut the detonating fuse 86 the saidangle members 94 snap intov an angular groove 96 in the case 72. Thus.is secured that type of charge unit within the carrier and, as isobvious, this type holding means for this type charge unit may, as withthe embodiment of Figures 1 and 2, be adapted for charges displacedtransversely at 90 intervals or phases. It will also be appreciated thatin the broad aspect of this invention other known embodiments of linedshaped charges not here shown may-be used without departing from thebroad principle of the invention.

While there. has been described what are at present considered.preferred embodiments of the present invention, it will be apparent tothose skilled in the art that various modifications and changes may bemade with out departing from the essence of the invention, and it isintended to cover herein all such modifications and changes as comewithin the true scope and spirit of the appended claims.

I claim:

1. A shaped charge carrier comprising: a hollow body, said body being ofpolygonal cross-section and consisting of a plurality of oppositelydisposed parallel face members, each of said face members being aflixedto its adjoining face members by means of connected edge flanges,opposite parallel face members having portions shaped to define supportmeans, shaped charge units carried by said support means oriented todirect their energy generally perpendicular to the respective parallelface members supporting them, said edge flanges extending outwardly ofsaid body to center the carrier and prevent rotation of the carrierwithin a well in which the carrier is lowered, and means holding saidshaped charge units in place on said support means.

2. A shaped charge carrier comprising a hollow body, said body being ofpolygonal cross-section and consisting of a plurality of oppositelydisposed parallel face members, each of said face members being aflixedto its adjoining face members by means of connected edge flanges,opposite parallel face members having portions shaped to define supportmeans, shaped charge units carried by said support means oriented todirect their energy generally perpendicular to the respective parallelface members supporting them, said edge flanges extending outwardly ofsaid body and having perforations therein, a detonating fuse woundthrough said perforations in helical disposition to and externally ofsaid face members, said fuse being connected to said shaped charge unitsso as to be capable of detonating them.

3. A shaped charge carrier comprising a hollow body, said body being ofpolygonal cross-section and consisting of a plurality of pairs ofsubstantially flat oppositely disposed parallel face members, each ofsaid face members being aflixed to its adjoining face members by meansof connected edge flanges, said edge flanges extending outwardly of saidbody to center the carrier and prevent rotation of the carrier within awell in which the carrier is lowered, axially spaced pairs oftransversely aligned front and rear shaped charge unit receivingopenings in said face member pairs, shaped charge units carried withinsaid openings oriented to direct their energy generally perpendicular tothe respective parallel face members supporting them, adjacent spacedpairs of openings being angularly offset with relation to each otherwhereby shaped charge units carried within said openings are set inangularly phased relationship. 1

4. A shaped charge carrier comprising a hollow body,

said body being of polygonal cross-section and consisting of a pluralityof pairs of substantially flat oppositely disposed parallel facemembers, each of said face members being affixed to its adjoining facemembers by means of connected edge flanges, said edge flanges extendingoutwardly of said body and having perforations therein, a detonatingfuse wound through said perforations in helical disposition to andexternally of said face members, said fuse being connected to shapedcharge units carried within axially spaced pairs of transversely alignedfront and rear openings in said face member pairs, adjacent spaced pairsof openings being angularly offset with relation to each other wherebythe said shaped charge units are set in angularly phased relationship.

5. A shaped charge carrier as in claim 1 wherein said mean holding saidshaped charge units in place comprise caps abutting said charge unitsand having laterally projecting lugs engageable with said support means.

6. A shaped charge carrier as in claim 1 wherein said means holding saidshaped charge units in place comprise grooves on said units and snapmembers on said face members engageable with said grooves.

References Cited in the file of this patent UNITED STATES PATENTS1,318,772 Koren Oct. 14, 1919 2,366,374 Whitesell Jan. 2, 1945 2,402,153Elliott June 18, 1946 2,494,256 Muskat Ian. 10, 1950 2,543,814 ThompsonMar. 6, 1951 2,649,046 Davis Aug. 18, 1953 2,680,406 Austin June 8, 19542,686,472 Burns Aug. 17, 1954 FOREIGN PATENTS 414,959 Great Britain Aug.16, 1934 OTHER REFERENCES Article by Robert H. McLemore entitledFormation Penetrating With Shaped Explosive Charges, published in TheOil Weekly, July 8, 1946, vol. 122, No. 6, pages 56 and 58.

Article by R. H. McLemore entitled Casing Perforating With ShapedExplosive Charges, published in The Oil and Gas Journal, issue ofDecember 28, 1946, 4 pages.

